www.basler.

com Model
ES-81O, ES-81U,
+1 618.654.2341 (USA)
info@basler.com
and ES-81O/U

INTRODUCTION Special Symbols

ES frequency relays provide frequency monitoring and Special symbols are located on the ratings label on
protection for use in single-phase or three-phase your ES series relay. These symbols are illustrated
applications. Three models are available: the ES-81O and described in Table 1.
provides overfrequency protection, the ES-81U pro- Table 1. Special Symbol Descriptions
vides underfrequency protection, and the ES-81O/U
provides overfrequency and underfrequency protec- Symbol Description
tion. Microprocessor-based circuitry enhances
functionality and improves performance. Internal Caution, Refer to Documentation
diagnostics annunciate when relay function or
accuracy is compromised. Caution, Risk of Electric Shock

Warning! SPECIFICATIONS

READ THIS MANUAL. Read this manual before

Operating Power
installing or operating your ES series relay. Note All units are self powered.
all warnings, cautions, and notes in this manual as Nominal Voltage: 120 Vac, 208 Vac, 240 Vac,
380 Vac, 415 Vac, or 480 Vac
well as on the product. Failure to follow warning
and cautionary labels may result in personal injury (For other nominal voltages, contact Basler Electric.)
or property damage. Exercise caution at all times. Frequency: 50 or 60 Hz
Burden: <2.5 VA per phase for narrow
It is the responsibility of the user to ensure that this case units, <3 VA per phase
product is installed, operated, and used for its for wide case units.
intended function in the manner specified by this Overload: 1.25 times nominal continuous
manual or any protection provided by this product 2 times nominal for 3 s
may be impaired.
Setpoint
Relay Adjustments 50 Hz Nominal
All ES frequency relays are equipped with a Set Overfrequency Range: 50 to 60 Hz
adjustment for underfrequency trips and/or over- Underfrequency Range: 40 to 50 Hz
frequency trips. Relays with instantaneous timing 60 Hz Nominal
have a Reset adjustment which allows the system to Overfrequency Range: 60 to 70 Hz
recover from load swings before dropping out and Underfrequency Range: 50 to 60 Hz
resetting the relay. Relays with adjustable timing have
a Delay adjustment which prevents premature relay Instantaneous Trip (Option)
operation during brief system frequency fluctuations. Adjustable Dropout: 0.1 to 3.0 Hz
Operating Time: <100 ms
Relay Output Contacts and Indicators Time Delayed Trip (Option)
ES frequency relays come equipped with output Adjustable Time Delay: 0 to 20 s
contacts and LED indicators. Relay output contacts Fixed Dropout: –0.1 Hz for overfrequency
can be used as an alarm annunciation, a control +0.1 Hz for underfrequency
output, or a tripping signal. A pair of form-C (SPDT)
Repeatability
output contacts and an LED indicator are provided for
±0.1 Hz
each protection function. A Power LED indicates the
presence of adequate sensing voltage when Output
continuously lit and annunciates any relay fault, Output contact trip performance is in accordance with
detected by internal diagnostics when flashing. IEEE Std C37.90™-2005 and IEC 60255-1.
Relay Type: SPDT (form-C)
Case Sizes AC Rating: 250 V, 5 A, non-resistive,
All ES-81O/U models are supplied in a wide case as 1,200 VA
are ES-81O and ES-81U models with auxiliary relay DC Rating: 125 V, 1 A, resistive, 120 W
outputs (style 1xxxNxA0). All other ES-81O and
ES-81U models are supplied in a narrow case. Environment
Operating Temperature: –40 to 70°C (–40 to 158°F)
Storage Temperature: –40 to 85°C (–40 to 185°F)

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Temperature Coefficient: 0.02% of nominal per °C EU directives:
(200 ppm/°C) • Low Voltage (LVD) 2006/95/EC
Relative Humidity: ≤95%, non-condensing • Electromagnetic Compatibility (EMC) 2004/108/EC
Ingress Protection: IP50 Case, IP20 Terminals • Hazardous Substances (RoHS 2) 2011/65/EU
Pollution: Degree 1 Harmonized standards used for evaluation:
Insulation: Class II • EN 50178
Overvoltage: Category III • EN 50581
Physical • EN 60255-1
Terminals • EN 60255-26
Type: Compression screw • EN 60255-27
Wire Size:
2
0.5-3.3 mm /20-12 AWG • IEC 61000-6-4
Screw Torque: 4.4 to 5.3 in-lb EAC (Eurasian Conformity)
(0.5 to 0.6 N•m) • TP TC 004/2011
Mounting (HxD): DIN rail 1.38 x 0.29 inches • TP TC 020/2011
(35 x 7.5 mm) complies
OPERATION
with IEC 60715
Size (WxHxD) Instantaneous Trip
Narrow Case: 2.17 x 2.75 x 4.38 inches Frequency protection in the ES-81O and ES-81U
(55 x 70 x 111 mm) relays with instantaneous trip (style 1xAxN2x0) is
Wide Case: 3.93 x 2.75 x 4.38 inches adjusted by two controls marked Set and Reset. The
(100 x 70 x 111 mm) ES-81O/U has four controls: Under Set, Over Set,
Weight Under Reset, and Over Reset.
Narrow Case: 0.85 lb (0.38 kg) Set Control
Wide Case: 1.10 lb (0.50 kg) The ES-81O relay Set control adjusts the
Applicable Standards overfrequency trip point. When the monitored
frequency rises above the trip point established by the
IEC
Set control, a relay trip occurs. This condition
IEC 60255-1 Measuring relays and protection energizes the relay output and lights the red
equipment – Part 1: Common requirements (includes Relay/Over LED. The overfrequency trip point is
all referenced/normative IEC standards) adjustable from 50 to 60 Hz at 50 Hz nominal and 60
IEEE to 70 Hz at 60 Hz nominal.
IEEE Std C37.90™-2005 – IEEE Standard for Relays The ES-81U relay Set control adjusts the
and Relay Systems Associated with Electric Power underfrequency trip point. When the monitored
Apparatus frequency drops below the trip point established by
IEEE Std C37.90.1™-2012 – IEEE Standard for Surge the Set control, a relay trip occurs. This condition
Withstand Capability (SWC) Tests for Relays and de-energizes the relay output and extinguishes the
Relay Systems Associated with Electric Power green Relay/Under LED. The underfrequency trip
Apparatus point is adjustable from 40 to 50 Hz at 50 Hz nominal
IEEE Std C37.90.2™-2004 – IEEE Standard for and 50 to 60 Hz at 60 Hz nominal.
Withstand Capability of Relay Systems to Radiated Reset Control
Electromagnetic Interference from Transceivers The ES-81O Reset control adjusts the overfrequency
IEEE Std C37.90.3™-2001 – IEEE Standard for dropout point. When the monitored frequency drops
Electrostatic Discharge Tests for Protective Relays below the trip point established by the Reset control,
the relay is de-energized and the red Relay/Over LED
Agency extinguishes.
UL The ES-81U Reset control adjusts the underfrequency
This product is listed to applicable Canadian and US dropout point. When the monitored frequency rises
safety standards and requirements by UL. above the trip point established by the Reset control,
• UL 508 the relay is energized and the green Relay/Under LED
• CSA C22.2 No. 0 lights.
• CSA C22.2 No. 14 The overfrequency and underfrequency dropout point
CE is adjustable from 0.1 to 3.0 Hz from the trip point.
This product has been evaluated and complies with
the relevant essential requirements set forth by the
EU legislation.

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Setting Example INSTALLATION
An ES-81O relay with a nominal input rating of 60 Hz ES relays should be installed in a dry location where
has the following settings: the ambient temperature remains within the operating
• Set - 65 Hz temperature range.
• Reset - 2 Hz ES frequency relays mount on standard DIN rails that
A trip occurs when the sensed frequency rises above comply with IEC 60715. Mounting involves hooking
65 Hz. The relay drops out when the frequency the top edge of the cutout on the base of the case
decreases below 63 Hz. over one edge of the DIN rail. The opposite side of the
cutout containing the release clip is then pushed over
Time Delayed Trip the opposite side of the DIN rail. To remove or
Frequency protection in the ES-81O and ES-81U reposition the relay, pull the release clip downward
relays with Time Delayed trip (style 1xBxN0x0) is and move the relay as required. Figure 1 shows the
adjusted by two controls marked Set and Delay. The dimensions of the ES-81O, ES-81U, and ES-81O/U
ES-81O/U has four controls: Under Set, Over Set, relays.
Under Delay, and Over Delay. Relay connections should be made using wire that
Set Control meets applicable codes and is properly sized for the
application. Figure 2 shows the sensing connections
The ES-81O relay Set control adjusts the
for the ES-81O, ES-81U, and ES-81O/U relays.
overfrequency trip point. When the monitored
Figure 3 illustrates the front panel appearance of
frequency rises above the trip point established by the
ES-81O and ES-81U relays with optional auxiliary
Set control for the duration of the adjustable time
relay outputs (style 1xxxNxA0).
delay, a relay trip occurs. This condition energizes the
relay output and lights the red Relay/Over LED. The
Caution
overfrequency trip point is adjustable from 50 to 60 Hz
at 50 Hz nominal and 60 to 70 Hz at 60 Hz nominal. Before commissioning, check the equipment
The ES-81U relay Set control adjusts the ratings, operating instructions, and installation
underfrequency trip point. When the monitored instructions.
frequency drops below the trip point established by
the Set control for the duration of the adjustable time CALIBRATION
delay, a relay trip occurs. This condition de-energizes The calibration marks on the faceplate are provided
the relay output and extinguishes the green only as guides. Proper calibration requires an
Relay/Under LED. The underfrequency trip point is accurate frequency meter in parallel with the input
adjustable from 40 to 50 Hz at 50 Hz nominal and 50 signal. Use the following procedure to calibrate your
to 60 Hz at 60 Hz nominal. relay.
Delay Control Instantaneous Overfrequency
The Delay control adjusts the amount of time that the 1. Adjust the Set and Reset controls fully clockwise
sensed input exceeds the pickup level before a relay (CW).
trip occurs. The time delay is adjustable from 0 to 20
2. Apply the desired trip frequency to the relay.
seconds.
3. Adjust the Set control counterclockwise (CCW)
Fixed Reset
until the relay trips.
An overfrequency dropout occurs when the frequency
4. Reduce the applied frequency to the desired reset
decreases 0.1 Hz below the trip point; the relay is
level.
de-energized and the red Relay/Over LED
extinguishes. An underfrequency dropout occurs 5. Adjust the Reset control CCW until the relay
when the frequency increases 0.1 Hz above the trip resets.
point; the relay is energized and the green Instantaneous Underfrequency
Relay/Under LED lights.
1. Adjust the Set control fully CCW and the Reset
Setting Example control fully CW.
An ES-81O relay with a nominal input rating of 60 Hz 2. Apply the desired trip frequency to the relay.
has the following settings:
3. Adjust the Set control CW until the relay trips.
• Set - 65 Hz 4. Increase the applied frequency to the desired
• Delay - 4 seconds reset level.
A trip occurs when the sensed frequency remains 5. Adjust the Reset control CCW until the relay
above 65 Hz for 4 seconds. The relay drops out when resets.
the frequency decreases below 64.9 Hz.

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Time Delayed Overfrequency 4. Increase the applied frequency and set the Delay
1. Adjust the Set control fully CW and the Delay control to the desired time delay.
control fully CCW. 5. Reduce the applied frequency to a level below the
2. Apply the desired trip frequency to the relay. trip level set in Step 3 and measure the time
delay.
3. Adjust the Set control CCW until the relay trips.
6. Adjust the Delay and repeat steps 4 and 5 until
4. Reduce the applied frequency and set the Delay the desired time delay is attained.
control to the desired time delay.
5. Increase the applied frequency to a level above MAINTENANCE
the trip level set in Step 3 and measure the time to ES relays require no maintenance. In the event that
trip. your relay requires repair, contact Basler Electric,
6. Adjust the Delay and repeat Steps 4 and 5 until Highland, IL, USA for return authorization.
the desired time delay is attained. ORDERING INFORMATION
Time Delayed Underfrequency Mounting accessories (DIN rails and DIN rail end
1. Adjust the Set and Delay controls fully CCW. stops) are available from Basler Electric. Table 1 lists
2. Apply the desired trip frequency to the relay. the part numbers for ordering.
3. Adjust the Set control CW until the relay trips. Figure 4 shows the ES frequency relay style number
identification chart.

FIGURES

Figure 1. Relay Dimensions

Figure 2. ES-81O, ES-81U, and ES-81O/U Sensing Connections

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 Figure 3. ES-81U and ES-81O Relays with Auxiliary Relay Outputs

Table 2. Mounting Accessories

Mounting Accessories Basler Part Number

DIN Rail, 3.0 inches (76 mm) wide 9323900001
DIN Rail, 5.5 inches (140 mm) wide 9323900002
DIN Rail, 8.0 inches (203 mm) wide 9323900003
DIN Rail, 39.4 inches (1,000 mm) wide 17366
DIN Rail End Stops 31761

MODEL NUMBER STYLE NUMBER

ES-81O, 81U, or 81O/U 1 N 0

Sensing Input Timing External Option 2 2

Type Power
A) Instantaneous N) None
1) Single-phase B) Adjustable, 0 to N) Not A) Two form-C
20 seconds required auxiliary relays

Nominal Frequency Option 1 1 Option 3

Input
2) 50 Hz 0) None 0) None
3
A) 120 Vac 3) 60 Hz 2) Adjustable reset
B) 208 Vac
C) 240 Vac
P0077-51

D) 380 Vac If Timing selection is A, then Option 1 selection must be 2.

1 If Timing selection is B, then Option 1 selection must be 0.
E) 415 Vac
F) 480 Vac
2 Option 2 selection A not available for ES-81O/U.
S) Special
Option 3 selection is "0" when standard voltage is selected for the Nominal
3 Input. Option 3 selection is the three-digit voltage value when a special (S)
Nominal Input is selected. To order an ES relay with special (S) Nominal
Input voltage, contact Basler Electric.
Figure 4. ES-81O, ES-81U, and ES-81O/U Style Number Identification Chart

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This device utilizes redistributable software code copyrighted by Freescale Semiconductor, Inc. The following copyright notice and
disclaimer are provided in this publication as required by the conditions for redistribution.
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• Neither the name of Freescale Semiconductor, Inc. nor the names of its contributors may be used to endorse or promote products
derived from this software without specific prior written permission.
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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